What is PCB membrane switch?

Membrane switch is a thin PET sheet with contacts, often be used as a switch in PCB, FPC and other circuit boards, and plays an important role in the touch switch between the user and the control device.  The contact on the film key is located on the conductive part of the PCB board (mostly located above the gold finger on the circuit board), when the key is pressed by external force, the center point of the contact is concave and contacts the circuit on the PCB, thus forming a loop, the current passes through, and the whole product can work normally.

Membrane switch is usually composed by “buttons + PET film”, so the click feeling, characteristics and tactile feeling depend on the design of the membrane switch. In considerate to the reliability of switch contact separation and rebound, the thickness of the PET film is generally selected at 0.125-0.2mm. If it is too thin and weak, and the contact separation is not sensitive. Too thick slow response to increase the operation force.

What are PCB circuit board Membrane Switches?

PCB always refers to FR4 PCB. FR-4, is a widely acceptable international grade destination for fiberglass reinforced epoxy laminated that are flame retardant (self-extinguishing). After add copper layer on one or each side FR4, it become to Copper Clad Laminate (CCL), and this is the non-conductive core material for normal printed circuit board (PCB). Printed circuit board using FR4 as core material will be named as “FR4 PCB”.

The PCB membrane switch utilizes a PCB as the main structure and support substrate, with the membrane switch on the front of the PCB, and some other components on the backside of the PCB.